code: def validate_tree(G, results):
      """Validate that jobs executed after their dependencies."""
      for node in G:
          started = results[node].metadata.started
          for parent in G.predecessors(node):
              finished = results[parent].metadata.completed
              assert (
                  started > finished
              ), "{} should have happened after {}".format(
                  node,
                  parent,
              )
  
file_path: ipyparallel/docs/source/examples/dagdeps.py
imports: from random import randint
  import networkx
  import ipyparallel
label_desc: Use image node_id 6 for calling a global function with example usage: validate_tree(G, results) without return types